1. Field of the Invention
The present invention relates to a microwave oven including a heater, in particular to a convection device of a microwave oven which is capable of providing the heat generated from a heater uniformly inside of a cooking chamber.
2. Description of the Prior Art
A microwave oven heats a heating object by using microwave. In recent years, in order to add more various heating function to the microwave oven, the heater is installed as the other heating source besides the microwave, and the heat generated by the heater is used for heating the heating object.
FIG. 1 illustrates the conventional microwave oven including the heater as the heating source besides the microwave. As depicted in FIG. 1, a heater chamber 4 is formed on the external upper portion of a cooking chamber 2, and heaters 6a, 6b are installed inside of the heater chamber 4.
A fan 10 is installed on the center portion of the heater chamber 4, the fan 10 is rotated by a motor M installed on the upper portion of the heater chamber 4. A sucking portion 8 and discharging portion 9a, 9b are formed on the upper surface of the cooking chamber 2 corresponding to the bottom surface of the heater chamber 4 in order to circulate air by the fan 10.
In more detail, the sucking portion 8 is formed on the lower center portion of the fan 10 in order to suck the air inside of the cooking chamber 2, and the discharging portion 9a, 9b are formed on the portion corresponding to the lower edge of the fan 10 in order to provide the air sucked through the sucking portion 8 to the inside of the cooking chamber 2.
In the conventional microwave oven, when the heating is performed by the heater 6a, 6b, the fan 10 operates at the same time with the heat generation of the heater 6a, 6b to which power has been applied. The air sucked from the cooking chamber 2 by the sucking portion 8 according to the operation of the fan 10 is heated while circulating inside of the heater chamber 4 and passing through the heater 6a, 6b, and is flowed into the cooking chamber 2 through the discharge portion 9a, 9b. 
However, the conventional convection heating type microwave oven has below problems.
In the heat convection, the heated-air circulating inside of the heater chamber 4 and cooking chamber 2 can not circulate sufficiently inside of the cooking chamber 2 while flowing through the sucking portion 8 on the center portion and the discharge portion 9a, 9b on the edge. In other words, the circulation of the heated-air is even on the upper center portion of the cooking chamber 2 adjacent to the fan 10, but the circulation of the heated-air on the lower portion such as a corner portion is not even.
In the heat convection of the convection heating type microwave oven, because the air-flow is generated by sucking the air on the center portion and using the centrifugal force of the fan 10 downwardly fixed, the appropriate air-flow for transmitting the heat to the overall cooking chamber 2 can not be generated. Accordingly, the foodstuff can not be uniformly heated because the conventional convection heating type microwave oven can not uniformly distribute the heat.
And, the air provided through the discharge portion 9a, 9b is the heated-air heated through the heat-exchange with the heater 6a, 6b, when the heated-air is provided to the inside of the cooking chamber 2, the heated-air contacts first with a side surface of the cooking chamber 2, accordingly the temperature of the heated-air lowers due to the heat loss. In other words, the heat transmission efficiency with the foodstuff lowers because the heat of the air is taken away to the side wall surface by contacting it first.
The object of the present invention is to provide a convection device of a microwave oven which is capable of transmitting uniformly the heat generated from a heater to each part inside of a cooking chamber.
The other object of the present invention is to provide the convection device of the microwave oven which is capable of providing selectively the heat generated from the heater to a predetermined portion inside of the cooking chamber.
In order to achieve the objects, the convection device of the present invention comprises a heater chamber installed on the side wall surface of the cooking chamber, a fan housing installed inside of the heater chamber so as to be rotational within a predetermined rotation range including an inlet hole where the air inside of the heater chamber flows into and a discharging port for providing the air into the cooking chamber, and a fan installed inner side surface of the fan housing for generating the air-flow provided inside of the cooking chamber through a discharging port.